1. Field of the Invention
The present invention relates to a beam scanner and a surface measurement apparatus, and more particularly, to abeam scanner and a surface measurement apparatus which can minimize errors caused by the movement of a spinning mirror for beam scanning.
2. Description of the Related Art
In general, semiconductor integrated circuits are fabricated by forming circuits on a wafer using a photolithography process. In this case, a plurality of the same integrated circuits are disposed on a wafer and divided into individual integrated circuit chips. If foreign bodies exist on the wafer, defective circuit patterns may be formed in the wafer portion where the foreign bodies exist. This may render the use of a corresponding integrated circuit impossible. As a result, integrated circuits obtainable from a single wafer decrease in number, and the yield is reduced. In addition to the semiconductor integrated circuits, examples of advanced materials that are adversely affected by foreign bodies or defects on the micrometer scale may include glass for display devices and materials for circuit boards. Accordingly, there is a need for equipment for measuring and inspecting such foreign bodies or defects.
In general, a method of collecting lasers on the surface of a wafer, receiving light scattered from a laser collection point on the wafer and detecting foreign bodies based on a signal corresponding to the received light is in use, to measure foreign bodies or defects on a wafer.
FIG. 1 is a schematic perspective view depicting a related art surface measurement apparatus.
Referring to FIG. 1, a related art surface measurement apparatus 10 includes a light source emitting laser beams (L), an object 11 of measurement, such as a wafer, and first and second beam detectors 12 and 13. The first beam detector 12 detects beams Ls scattered from the wafer 11. That is, light, scattered from a light collection point on the wafer 11, is collected in the first beam detector 12 serving as a photoelectric converter, through a lens. The first beam detector 12, having collected the scattered light, outputs a pulse signal corresponding to the intensity of beams scattered by foreign bodies. Thus, the sizes of the foreign bodies may be determined based on the magnitude of the output signal. The second beam detector 13 detects a beam Lr reflected by the wafer 11. By detecting signals by both scattered and reflected beams, the surface measurement apparatus 10 can determine the presence of foreign bodies on the wafer 11, measure the sizes of the foreign bodies and also measure the angle of the reflected beam to obtain a three-dimensional shape.